scheduledmessage.java

pastry的java实现的2.0b版

/*************************************************************************

"FreePastry" Peer-to-Peer Application Development Substrate 

Copyright 2002, Rice University. All rights reserved.

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- Redistributions of source code must retain the above copyright
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- Redistributions in binary form must reproduce the above copyright
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- Neither  the name  of Rice  University (RICE) nor  the names  of its
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this software without specific prior written permission.

This software is provided by RICE and the contributors on an "as is"
basis, without any representations or warranties of any kind, express
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********************************************************************************/
package rice.pastry;

import rice.environment.logging.Logger;
import rice.pastry.messaging.Message;
import rice.selector.TimerTask;

/**
 * A class that represents scheduled message events
 *
 * @version $Id: ScheduledMessage.java 2808 2005-11-22 15:38:49 +0100 (Tue, 22
 *      Nov 2005) jeffh $
 * @author Peter Druschel
 */
public class ScheduledMessage extends TimerTask {
  /**
   * DESCRIBE THE FIELD
   */
  protected PastryNode localNode;

  /**
   * DESCRIBE THE FIELD
   */
  protected Message msg;

  /**
   * Constructor
   *
   * @param pn DESCRIBE THE PARAMETER
   * @param msg DESCRIBE THE PARAMETER
   */
  public ScheduledMessage(PastryNode pn, Message msg) {
    localNode = pn;
    this.msg = msg;
  }

  /**
   * Returns the message
   *
   * @return the message
   */
  public Message getMessage() {
    return msg;
  }

  /**
   * Gets the LocalNode attribute of the ScheduledMessage object
   *
   * @return The LocalNode value
   */
  public PastryNode getLocalNode() {
    return localNode;
  }

  /**
   * deliver the message
   */
  public void run() {
    try {
      // timing with cancellation
      Message m = msg;
      if (m != null) {
        localNode.receiveMessage(msg);
      }
    } catch (Exception e) {
      Logger logger = localNode.getEnvironment().getLogManager().getLogger(getClass(), null);
      if (logger.level <= Logger.WARNING) {
        logger.logException("Delivering " + this + " caused exception ", e);
      }
    }
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @return DESCRIBE THE RETURN VALUE
   */
  public String toString() {
    return "SchedMsg for " + msg;
  }

  /*
   *  (non-Javadoc)
   *
   *  @see rice.p2p.commonapi.CancellableTask#cancel()
   */
  /**
   * DESCRIBE THE METHOD
   *
   * @return DESCRIBE THE RETURN VALUE
   */
  public boolean cancel() {
    // memory management
    msg = null;
    localNode = null;
    return super.cancel();
  }

}